They’ll have to do it against a ferocious season-opening gauntlet. The Bears debut under new coach Sonny Dykes on Saturday night against No. 22 Northwestern, which features the tag-team quarterback duo of Kain Colter (872 yards passing, 894 yards rushing) and Trevor Siemian (1,312 yards passing).

In Weeks 3 and 4, Cal faces a pair of top-5 teams with Heisman Trophy candidates at quarterback: Ohio State with Braxton Miller and Oregon with Marcus Mariota.

Can this secondary, without a senior in the starting lineup, take a punch and remain standing?

“That’s the question of our football team, quite frankly,” Dykes said. “We’re young. How are we going to respond when things don’t go well? I don’t think anybody knows. We think we’ll respond well, but we’ll see how it plays out.”

On the defensive side of the ball, no area is greener than the Bears’ secondary. Or more nicked up.

Sophomore cornerback Stefan McClure is back after missing all of 2012 with a serious knee injury. Junior strong safety Avery Sebastian hasn’t resumed full practice nearly two weeks after sustaining a concusion in a scrimmage.

Dykes said this week that redshirt freshman Demariay Drew “probably” would start against Northwestern, but believes Sebastian will be dressed and cleared to play by then.

Free safety Michael Lowe has been a part-time starter the past two seasons, but depth in the secondary is such a concern that linebacker Jason Gibson was transitioned to safey and wide receiver Joel Willis is being tried at corner.

“I think they’re coming together great,” defensive backs coach Randy Stewart said. “We’re thin in numbers, so we’ve had a lot of everybody in at some point.”

Stewart’s biggest concern is the lack of continuity in practice because of injuries. Among players on the depth chart, corner Adrian Lee (ankle), safety Alex Logan (foot) and Gibson (hamstring) all have missed time recently.

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Dykes got a Cal history lesson recently from four former quarterbacks. Dykes called an evening out for dinner with Troy Taylor, Mike Pawlawski, Dave Barr and Pat Barnes “a heck of a deal, a lot of fun, very insightful for me.”

During the 1980s and ’90s. those four combined to pass for more than 15 miles with 193 touchdowns.

“I tried to listen as much as I could, kind of soak in what they had to say about ways to connect with former players and improve our program,” said Dykes, adding that he wants to embrace Cal’s football alumni.

“That’s a huge resource for us,” he said. “Those guys have laid it on the line and put a lot into this program. They care a lot about it. The least we can do is welcome them back with open arms.”

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Dykes has not ruled out backup Zach Kline getting some playing time against Northwestern. “I wouldn’t be surprised if he did,” he said, adding he’s not sure what the circumstances would be.

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Two sources said Cal players will wear No. 42 decals on their helmets this season to honor the late Chuck Muncie, the running back who finished second in the 1975 Heisman Trophy voting.

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Seniors Jackson Bouza and Deandre Coleman and sophomores Freddie Tagaloa and Stefan McClure were voted team captains for the season by their teammates.